Temperature Control of Terahertz Metamaterials With Liquid Crystals

Liu, Liming; Shadrivov, Ilya V.; Powell, David A.; Raihan, Rezaur; Hattori, Haroldo T.; Decker, Manuel; Mironov, Evgeny G.; Neshev, Dragomir N.

doi:10.1109/tthz.2013.2285570

Cited by 31 publications

(21 citation statements)

References 23 publications

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“…Various types of active metasurfaces employ different mechanisms for tuning the liquid crystal, i.e. applying electric field 99,100,108,[197][198][199][200][201][202][203][204][205][206][207][208][209][210][211][212][213] , magnetic field 67,68 , optical pumping 101,214 , or thermal heating 102,103,109,215,216 . New types of light-driven plasmonic color filters by (e, f) ref.…”

Section: Liquid Crystals (Lcs)mentioning

confidence: 99%

Tunable and reconfigurable metasurfaces and metadevices

Nemati

Wang

Hong

et al. 2018

Opto-Electronic Advances

318

205

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Metasurfaces, two-dimensional equivalents of metamaterials, are engineered surfaces consisting of deep subwavelength features that have full control of the electromagnetic waves. Metasurfaces are not only being applied to the current devices throughout the electromagnetic spectrum from microwave to optics but also inspiring many new thrilling applications such as programmable on-demand optics and photonics in future. In order to overcome the limits imposed by passive metasurfaces, extensive researches have been put on utilizing different materials and mechanisms to design active metasurfaces. In this paper, we review the recent progress in tunable and reconfigurable metasurfaces and metadevices through the different active materials deployed together with the different control mechanisms including electrical, thermal, optical, mechanical, and magnetic, and provide the perspective for their future development for applications.

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Section: Liquid Crystals (Lcs)mentioning

confidence: 99%

Tunable and reconfigurable metasurfaces and metadevices

Nemati

Wang

Hong

et al. 2018

Opto-Electronic Advances

318

205

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“…One reason for the reduced sensitivity in these studies was imperfect alignment of molecules in the vicinity of the optical scatterer or surface anchoring of the molecules to the scatterer. Several LC‐tunable metamaterials in the microwave or far infrared regime were demonstrated with measured spectral shifts of the resonance frequency ranging from 1.5% to 4% . These structures proved less sensitive to surface anchoring due to their near‐field extending over larger distances and thus an interaction with a larger volume of the LCs.…”

Section: Adaptive Metasurfacesmentioning

confidence: 99%

Optical Metasurfaces: Evolving from Passive to Adaptive

Hail

Michel

Poulikakos

et al. 2019

Advanced Optical Materials

116

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of ultrathin, artificial surfaces, so-called metasurfaces, for manipulating the propagation of light at will. [1,2] Metasurfaces control the propagation of light by abruptly changing its phase, amplitude, polarization, or spectrum at a surface and within a thin (quasi-2D) layer using large arrays of optical scatterers with subwavelength separation. Ideally, each scatterer can be independently engineered in order to locally influence the wavelets of the impinging light, and therefore, arbitrarily reform the wavefront. This concept has been exploited to create a variety of flat optical elements such as beam deflectors, [3][4][5] lenses, [6][7][8] and holograms. [9,10] As compared to bulky refraction-based optical elements, these surfaces are of subwavelength or wavelength-scale thickness, which enables their integration into compact devices. A main feature of the majority of such flat optical elements is that they are passive, and once fabricated, their optical functionalities are invariable. A beam deflector of this kind will direct light of a certain wavelength and direction always into the same direction, or a lens will focus light always to the same focal point. A broad range of new applications could be enabled if it were possible to actively and reversibly change the functionality of metasurfaces after their fabrication. With such "adaptive" metasurfaces beam deflectors with adjustable angle of deflection, metalenses with variable focal length or dynamic holograms may be realized. Advances toward such active devices are highly relevant for applications such as light detection and ranging [11] (LIDAR) sensing for driverless cars, dynamic zoom lenses for miniaturized camera systems [12] (e.g., in smartphones), or holographic displays for augmented reality devices. [13] An adaptive metasurface allows for the dynamic adjustment of an optical functionality of the surface. As shown in Figure 1, for the specific case of a metalens, these surfaces can be categorized based on their degree of dynamic adaptivity. While a passive surface has a fixed functionality, a switchable metasurface allows for switching back and forth between two (or more) predefined states (e.g., switching between different focal lengths, deflection angles, or hologram images). A continuously tunable metasurface enables continuous adjustment of a property within a range (e.g., tunable focal length or deflection angle). Finally, a freely tunable metasurface allows for continuous, arbitrary adjustment of a property, for example, 3D adjustment of the focal point of the metalens shown in Figure 1. Adaptive functionalities can be added to metasurfaces with different methods, for example, by mechanically rearranging the scatterers on the surface with respect to each other, or modifying

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“…In particular, great efforts have been placed in the terahertz (THz) range, where there is a high demand for wave manipulating devices. For THz metamaterials, tunability can be achieved by using materials like semiconductors 6 or liquid crystals, 7 the properties of which can be changed by applying voltage or by changing the temperature of the device. Alternative ways to get larger resonance tunability include changing the geometry directly or manipulating the coupling between adjacent metamaterial layers in multi-layer metamaterials.…”

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confidence: 99%

Terahertz focusing of multiple wavelengths by graphene metasurfaces

Liu

Zárate

Hattori

et al. 2016

Applied Physics Letters

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Metasurfaces can achieve nearly arbitrary wavefront control based on manipulation of the wave phase profile. We propose a metasurface based on double graphene cut-wire resonators which can cover the complete 2π phase region with high reflection efficiency. This full phase coverage is essential for efficient wavefront manipulation, without reflecting energy into unwanted channels. A mirror capable of focusing multiple wavelengths is demonstrated numerically based on the proposed structure. The mirror can effectively focus terahertz (THz) waves from 1.2 to 1.9 THz to the same focal point by changing the Fermi level of each graphene resonator separately. The presented metasurface could provide a powerful platform for controlling THz waves, including focusing, beam steering, beam shaping, and holography.

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Temperature Control of Terahertz Metamaterials With Liquid Crystals

Cited by 31 publications

References 23 publications

Tunable and reconfigurable metasurfaces and metadevices

Tunable and reconfigurable metasurfaces and metadevices

Optical Metasurfaces: Evolving from Passive to Adaptive

Terahertz focusing of multiple wavelengths by graphene metasurfaces

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